Problem solved!

Hello Billy and Thomas,

I replaced the blend pot with another one I had ordered here in Germany (at
least I think
so, maybe I confused the pots, but both were sold as balance pots 500K).
The old one reads "A500K" on the top and has a round plate at the bottom for the
center
dent.

The "new" working one reads: "ALPS" (so it seems to be an ALPS, though it was
not
advertised as one) stamped into the metal on one side and has no plate for the
center
dent, it seems the center dent is made inside the pot.

Though its a bit tiny with a small shaft, it works great.

So I can't tell what the right pot is logarithmic/audio taper or linear, because
I don't know
what type the "ALPS" is.

Joey (FODERA Guitars)mailed me:"It sound like the pot that you put in has a
different taper
or the pot itself is not wired. I can send you a pan pot that will work. "

Very nice of them, they wanted to send it free of charge, but I don't need it
anymore.

But I'm not totally satisfied, because I'm curious and like to know why and how
things
work...

Thank You all for Your suggestions!

Hartmut